Electric working machine

ABSTRACT

An electric working machine in one aspect of the present disclosure includes a motor and a controller. The motor is configured to be electrically coupled to a battery pack and to be driven with electric power from the battery pack. The controller is configured to acquire an internal resistance information of the battery pack and to change control of the motor based on the internal resistance information acquired.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Japanese Patent Application No.2019-172073 filed on Sep. 20, 2019 with the Japan Patent Office,disclosure of which is incorporated herein by reference.

BACKGROUND

The present disclosure relates to an electric working machine.

An electric power tool disclosed in Japanese Unexamined PatentApplication Publication No. 2005-131770 is a type of electric workingmachine that includes a motor driven with electric power from a batterypack.

SUMMARY

In recent years, battery packs have been diversified and there have beena variety of types of battery packs having the same rated voltage. Underthese circumstances, some motors stop as they experience overcurrent butsome do not stop as they do not experience overcurrent, depending on thecombination of the battery pack and the electric working machine.Likewise, some electric working machines may experience a delayedstart-up but some may not, depending on the above-described combination.That is to say, some electric working machines do not appropriatelyoperate depending on the combination with the battery pack.

It is preferable in one aspect of the present disclosure to provide anelectric working machine that can appropriately operate regardless ofwhich battery pack is combined with.

An electric working machine according to one aspect of the presentdisclosure includes a connection port, a motor and a controller. Theconnection port is coupled to the battery pack. The motor is configuredto be driven with electric power from the battery pack via theconnection port. The controller acquires an internal resistanceinformation related to an internal resistance value of the battery pack,and changes control of the motor based on the internal resistanceinformation acquired.

According to one aspect of the present disclosure, the internalresistance information is acquired and then the control of the motor ischanged based on the internal resistance information acquired. Theinventor has acquired a knowledge that when a battery pack having arelatively large internal resistance value is coupled to an electricworking machine in which control of the motor is adapted for a batterypack having a relatively small internal resistance value, a start-up ofthe electric working machine may be delayed or output of the electricworking machine may decline. The inventor has also acquired a knowledgethat when a battery pack having a relatively small internal resistancevalue is coupled to an electric working machine in which control of themotor is adapted for a battery pack having a relatively large internalresistance value, an excessive current may flow at a start-up of theelectric working machine and may result in stopping of the motor. Thecontrol of the motor is changed based on the internal resistanceinformation, whereby an appropriate operation of the electric workingmachine can be achieved.

The control of the motor may include control related to the start-up ofthe motor.

The control related to the start-up of the motor is changed based on theinternal resistance information, whereby stopping of the motor due to anexcessive current and a delayed start-up of the motor are suppressedregardless of the internal resistance value of the battery pack, and themotor can be appropriately started.

The controller may be configured to set a startup parameter related tothe start-up of the motor based on the internal resistance information.

The startup parameter of the motor is set based on the internalresistance information, whereby the control related to the start-up ofthe motor can be changed in accordance with the internal resistanceinformation.

A switch for driving the motor may be provided. The controller mayperform an open loop control of the motor based on a Pulse WidthModulation (PWM) signal of a command duty ratio. The command duty ratiocorresponds to a command value of the PWM signal. The controller mayperform a soft start in the open loop control in response to switchingof the switch to ON in order to gradually increase the command dutyratio to a target duty ratio. The target duty ratio corresponds to atarget value of the duty ratio. The controller may change a first termbased on the internal resistance information in the soft start. Thefirst term corresponds to a time period required for the command dutyratio to reach the target duty ratio in response to switching of theswitch to ON.

When the first term is set constant in the soft start, a voltage appliedto the motor is increased and a value of a current flowing in the motoris increased in accordance with a decrease in the internal resistancevalue. Then, the first term is changed based on the internal resistanceinformation in the soft start. This can suppress a flow of an excessivecurrent to the motor regardless of the internal resistance value.

A switch for driving the motor may be provided. The controller mayexecute a constant rotation speed control to adjust a rotation speed ofthe motor to be consistent with a command rotation speed. The commandrotation speed corresponds to a command value of the rotation speed. Thecontroller may perform a soft start in the constant rotation speedcontrol in response to switching of the switch to ON in order togradually increase the command rotation speed to a target rotationspeed. The target rotation speed corresponds to a target value of therotation speed. The controller may change a second term based on theinternal resistance information in the soft start. The second termcorresponds to a time period required for the command rotation speed toreach the target rotation speed in response to switching of the switchto ON.

When the second term is set constant in the soft start, a voltage dropin the battery pack is increased in accordance with the increase in theinternal resistance value. A current flowing to the motor is accordinglyincreased. Then, the second term is changed based on the internalresistance information in the soft start. This can suppress a flow of anexcessive current to the motor regardless of the internal resistancevalue.

The startup parameter may include a first rate of change. The first rateof change corresponds to a rate of change in the command duty ratio.

The first rate of change is changed based on the internal resistanceinformation, whereby the first term can be changed.

The controller may acquire the internal resistance value based on theinternal resistance information. The controller may set the first rateof change so that the first rate of change is decreased in accordancewith the decrease in the internal resistance value.

With the configuration where the first rate of change is set so that thefirst rate of change is decreased in accordance with the decrease in theinternal resistance value, a sharp increase in current value at thestart-up of the motor can be suppressed even when the internalresistance value is relatively small. Consequently, an excessive currentat the star-up of the motor can be suppressed even when the internalresistance value is relatively small.

The startup parameter may include a second rate of change. The secondrate of change corresponds to a rate of change in the command rotationspeed.

The second rate of change is changed based on the internal resistanceinformation, whereby the second term can be changed.

The controller may acquire the internal resistance value based on theinternal resistance information. The controller may set the second rateof change so that the second rate of change is decreased in accordancewith the increase in the internal resistance value.

With the configuration where the second rate of change is set so thatthe second rate of change is decreased in accordance with the increasein the internal resistance value, a sharp increase in current value atthe start-up of the motor can be suppressed even when the internalresistance value is relatively large. Consequently, an excessive currentat the star-up of the motor can be suppressed even when the internalresistance value is relatively large.

The control of the motor may include control related to outputrestriction of the motor.

The control related to output restriction of the motor is changed basedon the internal resistance information. Because of this, output of themotor can be appropriately controlled regardless of the internalresistance value.

The controller may control a discharge current to be equal to or below aset upper limit of the current value. The discharge current flows fromthe battery pack to the motor. The controller may acquire the internalresistance value based on the internal resistance information. Thecontroller may set a current limit value so that the current limit valueis decreased in accordance with the decrease in the internal resistancevalue.

Since the voltage drop in the battery pack is decreased in accordancewith the decrease in the internal resistance value, the voltage appliedto the motor is increased in accordance with the decrease in theinternal resistance value. Thus, the current limit value is set thecurrent limit value so that the current limit value is decreased inaccordance with the decrease in the internal resistance value, wherebyoutput of the motor can be controlled constant regardless of theinternal resistance value.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments of the present disclosure will be describedhereinafter by way of example with reference to the accompanyingdrawings, in which:

FIG. 1 is a block diagram showing structures of an electric workingmachine and a battery pack according to a first embodiment;

FIG. 2 is a flowchart illustrating a main process executed by amicrocomputer according to the first embodiment;

FIG. 3 is a flowchart illustrating a battery state process executed bythe microcomputer according to the first embodiment;

FIG. 4 is a flowchart illustrating a battery communication processaccording to the first embodiment;

FIG. 5 is a flowchart illustrating a motor control process according tothe first embodiment;

FIG. 6 is a flowchart illustrating a motor driving process according tothe first embodiment;

FIG. 7 is a flowchart illustrating a command duty ratio setting processaccording to the first embodiment;

FIG. 8 is a time chart of a command duty ratio, a discharge currentvalue and a trigger switch state when a rate of change in the commandduty ratio is set constant;

FIG. 9 is a time chart of the command duty ratio, the discharge currentvalue and the trigger switch state according to the first embodiment;

FIG. 10 is a flowchart illustrating a motor driving process according toa second embodiment;

FIG. 11 is a flowchart illustrating a command rotation speed settingprocess according to the second embodiment;

FIG. 12 is a time chart of a command rotation speed, a discharge currentvalue and a trigger switch state when the rate of change in the commandrotation speed is set constant;

FIG. 13 is a time chart of the command rotation speed, the dischargecurrent value and the state of the trigger switch state according to thesecond embodiment;

FIG. 14 is a flowchart illustrating a motor driving process according toa third embodiment;

FIG. 15 is a flowchart illustrating a current limit value settingprocess according to the third embodiment;

FIG. 16 is a view showing a relationship among an internal resistance ofthe battery, a battery output voltage and a discharge current;

FIG. 17 is a view showing a current limit value used in each of cases ofduring authentication and where authentication is successful accordingto the third embodiment;

FIG. 18 is a view showing a current limit value used in each of cases ofduring authentication and where authentication is failed according tothe third embodiment;

FIG. 19 is a view showing an overload map, an internal resistance valueof the battery pack and a threshold value of overcurrent used in each ofcases of waiting for authentication, where authentication is failed andwhere authentication is successful according to the third embodiment;and

FIG. 20 is a view showing an example of the overload map according tothe third embodiment.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS First Embodiment

<1-1. Configuration>

<1-1-1. Electrical Configuration of Battery Pack>

A description will be given of electrical configurations of a firstbattery pack 70A and a second battery pack 70B, with reference toFIG. 1. The first, the second battery packs 70A, 70B have the same ratedvoltage and different internal resistance values. The first, the secondbattery packs 70A, 70B basically have the same configuration. The first,the second battery packs 70A, 70B are repeatedly chargeable powersources and are, for example, lithium ion secondary batteries.

The first, the second battery packs 70A, 70B, each include: one or morebattery blocks 80; a control circuit 75; a battery positive terminal 71;a battery negative terminal 72; a battery signal terminal 73; andbattery serial communication terminals 74A, 74B.

The number of the battery blocks 80 provided in the first battery pack70A differs from the number of the battery blocks 80 provided in thesecond battery pack 70B. The configuration of the first battery pack 70Ais the same as that of the second battery pack 70B except for the numberof the battery blocks 80. Each of the battery blocks 80 includes batterycells coupled in series. Each of positive electrodes of the batteryblocks 80 is coupled to the battery positive terminal 71, and each ofnegative electrodes of the battery blocks 80 is coupled to the batterynegative terminal 72.

In the present embodiment, the first battery pack 70A includes a singlebattery block 80. Meanwhile, the second battery pack 70B includes twobattery blocks 80 coupled in parallel. Thus, an internal resistancevalue of the first battery pack 70A is larger than an internalresistance value of the second battery pack 70B.

The control circuit 75 includes: a CPU 76; and a memory 77. The memory77 is a semiconductor memory including a volatile memory and anon-volatile memory. The CPU 76 executes various programs stored in thememory 77, thereby executing various processes.

Specifically, the control circuit 75 outputs a discharge permissionsignal to an electric working machine 10 via the battery signal terminal73 when the battery block 80 is dischargeable. The control circuit 75also outputs a discharge prohibition signal to the electric workingmachine 10 via the battery signal terminal 73 when the battery block 80is not dischargeable. The discharge permission signal is, for example, alow-level signal, and the discharge prohibition signal is, for example,a high-level signal.

The control circuit 75 executes a full duplex serial communication withthe electric working machine 10 via the battery serial communicationterminals 74A, 74B. Specifically, the control circuit 75 transmits aserial signal including information of the first, the second batterypacks 70A, 70B to the electric working machine 10 via the battery serialcommunication terminal 74B, and receives a serial signal includinginformation of the electric working machine 1 from the electric workingmachine 10 via the battery serial communication terminal 74A.

<1-1-2. Electrical Configuration of Electric Working Machine>

A description will be given of an electrical configuration of theelectric working machine 10, with reference to FIG. 1. The electricworking machine 10 is a working machine, such as an electric power tooland a gardening tool, in which a tip tool is driven by a driving forceof a motor. Examples of the electric power tool may include a circularsaw, a driver drill, an impact screwdriver, a cleaner, and a hammerdrill. Examples of the gardening tool may include a grass cutter, atrimmer, and a blower.

The electric working machine 10 includes: a controller 20; a motor 60; arotation sensor 26; and a tip tool 61. The electric working machine 10is driven with electric power from the first battery pack 70A or thesecond battery pack 70B.

The motor 60 is a three-phase brushless motor. The motor 60 is coupledto the tip tool 61. The tip tool 61 is driven by receiving a rotationalforce from the motor 60. The rotation sensor 26 includes, for example, ahall IC to detect a rotational position of a rotor of the motor 60. Therotation sensor 26 outputs the detected rotational position of the rotorto a later-described microcomputer 30. The microcomputer 30 calculates arotation speed of the motor 60 from the rotational position of the rotorobtained from the rotation sensor 26 and a detection time interval.

The controller 20 includes: a positive terminal 11; a negative terminal12; a signal terminal 13; and serial communication terminals 14A, 14B.The positive terminal 11 is coupled to the battery positive terminal 71.The negative terminal 12 is coupled to the battery negative terminal 72.The signal terminal 13 is coupled to the battery signal terminal 73. Theserial communication terminal 14A is coupled to the battery serialcommunication terminal 74A, and the serial communication terminal 14B iscoupled to the battery serial communication terminal 74B.

The controller 20 further includes: a regulator 21; a battery voltagedetector 22; a trigger switch 23; a Light Emitting Diode (LED) display24; a current detection circuit 25; the microcomputer 30; a gate circuit40; and a drive circuit 50.

The regulator 21 generates a power-supply voltage required foractivating the microcomputer 30 (for example, direct-current 5V) byreceiving power supply from one or two battery blocks 80 when the firstbattery pack 70A or the second battery pack 70B is coupled to theelectric working machine 10.

The battery voltage detector 22 detects voltage values of the first, thesecond battery packs 70A, 70B applied between the positive terminal 11and the negative terminal 12 and outputs the detected voltage values tothe microcomputer 30.

The trigger switch 23 is operated by a user of the electric workingmachine 10 to drive or to stop the motor 60. The trigger switch 23 isswitched from OFF to ON when pulled by the user, and then outputs an ONsignal to the microcomputer 3. The trigger switch 23 is switched from ONto OFF when released by the user, and then outputs an OFF signal to themicrocomputer 30.

The trigger switch 23 is operated by the user to adjust the rotationspeed and/or a torque of the motor 60. A pulse-width modulated pulse(that is, a PWM signal) is applied to windings of the motor 60 based ona command duty ratio. The command duty ratio is a command value of eachof duty ratios for first to sixth switching devices Q1 to Q6 provided inthe later-described drive circuit 50, and generated by the microcomputer30. A target duty ratio is a target value of the command duty ratio, andis set in accordance with pulling amount of the trigger switch 23 by theuser. The user adjusts the pulling amount of the trigger switch 23depending on how much rotation speed and/or torque the user desires themotor 60 to rotate with. For example, when the user desires the rotationspeed of the motor 60 to be relatively low, and/or desires the torque tobe relatively small, the pulling amount of the trigger switch 23 isadjusted to be relatively small. When the user desires the rotationspeed of the motor 60 to be relatively high, and/or desires the torqueto be relatively large, the pulling amount of the trigger switch 23 isadjusted to be relatively large.

A switch and/or a dial other than the trigger switch 23 may be providedfor the user to set an operation mode and/or the target duty ratio ofthe electric working machine 10. The target duty ratio may be set inaccordance with the operation mode.

The display LED 24 notifies the user of an operation state and/orfailure of the electric working machine 10. The display LED 24 includesa plurality of LEDs to display information such as the operation mode ofthe electric working machine 10, the rotation speed and a rotationaldirection of the motor 60, remaining energy of the first, the secondbattery packs 70A, 70B. Each LED of the display LED 24 is accordinglyturned on the light, blinks, or is turned off the light as commanded bythe microcomputer 30.

The drive circuit 50 supplies electric current to windings correspondingto the respective phases of the motor 60 by receiving power supply fromthe first, the second battery packs 70A, 70B. The drive circuit 50 is athree-phase full-bridge circuit including the first to third switchingdevices Q1 to Q3 at a high side and the fourth to sixth switchingdevices Q4 to Q6 at a low side. Each of the first to sixth switchingdevices Q1 to Q6 is, for example, in a form of metal-oxide-semiconductorfield-effect transistor (MOSFET), but is not limited to MOSFET.

The gate circuit 40 sequentially supplies electric current to windingsof the respective phases of the motor 60 by turning each of the first tosixth switching devices Q1 to Q6 of the drive circuit 50 ON or OFF inaccordance with the command duty ratio outputted from the microcomputer30 to rotate the motor 60. When all the first to sixth switching devicesQ1 to Q6 are turned OFF, the motor 60 enters a free-running state. Whenall of the first to third switching devices Q1 to Q3 are turned OFF andall of the fourth to sixth switching devices Q4 to Q6 are turned ON, themotor 60 enters a state in which a so-called short-circuit braking workson the motor 60.

The current detection circuit 25 is disposed on a negative electrodeline extending from a drive circuit 50 to the negative terminal 12, anddetects a value of discharge current outputted from the first, thesecond battery packs 70A, 70B to the motor 60. The current detectioncircuit 25 outputs the detected value (hereinafter referred to asdischarge current value) to the microcomputer 30.

The microcomputer 30 includes: a CPU 31; and a memory 32. The memory 32is a semiconductor memory including a volatile memory and a non-volatilememory. The CPU 31 executes various programs stored in the memory 32,thereby executing various processes. The processes executed by themicrocomputer 30 will be described later.

<1-2. Process>

<1-2-1. Main Process>

A description will be given of a main process executed by themicrocomputer 30 of the electric working machine 10, with reference tothe flowchart shown in FIG. 2. The first battery pack 70A or the secondbattery pack 70B is coupled to the electric working machine 10.Hereinafter, the first battery pack 70A or the second battery pack 70Bcoupled to the electric working machine 10 will be referred to as abattery pack 70.

In S10, the microcomputer 30 first determines whether or not apredetermined term has elapsed. The microcomputer 30 waits if thepredetermined term has not elapsed, but proceeds to process in S20 ifthe predetermined term has elapsed. The predetermined term correspondsto a cycle for controlling the microcomputer 30.

In S20, the microcomputer 30 executes a switch manipulation detectionprocess. Specifically, the microcomputer 30 detects whether the triggerswitch 23 is in an ON state or in an OFF state based on a signal fromthe trigger switch 23.

In S30, the microcomputer 30 executes a battery state process based oninformation outputted from the battery pack 70. The battery stateprocess will be detailed later.

In S40, the microcomputer 30 executes an Analog to Digital (A-D)conversion process. Specifically, the microcomputer 30 converts ananalog detection signal outputted from the battery voltage detector 22,the current detection circuit 25 or the like, into a digital signal. Inthis way, the microcomputer 30 acquires a value of the discharge currentflowing from the battery pack 70 to the motor 60, the voltage value ofthe battery pack 70, or the like.

In S50, the microcomputer 30 executes a failure detection process.Specifically, the microcomputer 30 compares the discharge current value,the voltage value or the like acquired in S40 with the respectivethreshold values, thereby detecting a failure such as an overcurrent anda voltage drop.

In S60, the microcomputer 30 executes a motor control process based onthe state of the trigger switch 23, the battery state, and the detectionresult of the failure. The motor control process will be detailed later.

In S70, the microcomputer 30 executes a display process. Specifically,the microcomputer 30 notifies the user of information such as theoperation state of the motor 60, the remaining energy of the batterypack 70, and the detected failure via the display LED 24. Then, thepresent process is terminated.

<1-2-2. Battery State Process>

Hereinafter, a detailed description will be given of the battery stateprocess executed by the microcomputer 30 in S30, with reference to theflowchart in FIG. 3.

In S100, the microcomputer 30 executes a battery communication process.The battery communication process will be detailed later.

In S110, the microcomputer 30 executes a discharge permission statesetting process. Specifically, the microcomputer 30 sets a dischargepermission flag upon receiving the discharge permission signal from thebattery pack 70 via the signal terminal 13. The microcomputer 30 clearsthe discharge permission flag upon receiving the discharge prohibitionsignal via the signal terminal 13. Then, the present process isterminated.

<1-2-3. Battery Communication Process>

Hereinafter, a detailed description will be given of the batterycommunication process executed by the microcomputer 30 in S100, withreference to the flowchart in FIG. 4.

In S200, the microcomputer 30 determines whether or not an initialcommunication is completed. When determining in S200 that the initialcommunication is not completed, the microcomputer 30 proceeds to processin S210, but when determining that the initial communication iscompleted, the microcomputer 30 proceeds to process in S220.

In S210, the microcomputer 30 executes an initial communication process.Specifically, the microcomputer 30 transmits information of the electricworking machine 10, such as model number of the electric working machine10, to the battery pack 70 via the serial communication terminal 14A.The microcomputer 30 receives an internal resistance information, amodel number of the battery pack 70, or such from the battery pack 70via the serial communication terminal 14B. The internal resistanceinformation may be the internal resistance value of the battery pack 70or the number of the battery blocks 80 coupled in parallel. That is tosay, the internal resistance information may be the internal resistancevalue, or information from which the internal resistance value can becalculated or estimated.

Meanwhile, in S220, a constant information acquisition process isexecuted. Specifically, the microcomputer 30 receives temperature,remaining energy and a later-described overload counter value of thebattery pack 70 via the serial communication terminal 14B. Then, thepresent process is terminated.

<1-2-4. Motor Control Process>

Hereinafter, a detailed description will be given of the motor controlprocess executed by the microcomputer 30 in S60, with reference to theflowchart in FIG. 5.

In S300, the microcomputer 30 determines whether or not the triggerswitch 23 is in an ON state. When determining that the trigger switch 23is in the ON state, the microcomputer 30 proceeds to process in S310,but when determining that the trigger switch 23 is in an OFF state, themicrocomputer 30 proceeds to process in S340.

In S310, the microcomputer 30 determines whether or not a failure hasbeen detected in S50. When determining that any failure has not beendetected, the microcomputer 30 proceeds to process in S320. Whendetermining that a failure has been detected, the microcomputer 30proceeds to process in S340.

In S320, the microcomputer 30 determines whether or not the dischargepermission flag is set. When determining that the discharge permissionflag is set, the microcomputer 30 proceeds to process in S330, but whendetermining that the discharge permission flag is cleared, themicrocomputer 30 proceeds to process in S340.

In S330, the microcomputer 30 executes a motor driving process byreceiving power supply from the battery pack 70 and then terminates thisprocess. The motor driving process will be detailed later.

Meanwhile, in S340, the microcomputer 30 determines whether or not toperform a braking control. Specifically, the microcomputer 30 determinesto perform the braking control when the controller 20 is not affected bya braking force generated on the motor 60 while the motor 60 isrotating. In this case, the microcomputer 30 sets a braking flag inS350, and then terminates this process. This stops power supply from thebattery pack 70 to the motor 60, and then the short-circuit braking isperformed.

The microcomputer 30 determines not to perform the braking control whenthe motor 60 is not rotating, and when the controller 20 is affected bythe braking force generated on the motor 60 while the motor 60 isrotating. In such a case, the microcomputer 30 clears the braking flagin S360, and then terminates this process. This stops power supply fromthe battery pack 70 to the motor 60. When the motor 60 is rotating, thefree running or the like is executed. Then, the present process isterminated.

<1-2-5. Motor Driving Process>

A detailed description will be given of the motor driving processexecuted by the microcomputer 30 in S330, with reference to theflowchart in FIG. 6.

In S400, the microcomputer 30 executes a command duty ratio settingprocess. In the present embodiment, the microcomputer 30 executes aPulse Width Modulation (PWM) control in which a pulse with the setcommand duty ratio is applied to the windings of the motor 60. Thecommand duty ratio setting process will be detailed later.

In S410, the microcomputer 30 executes a command duty ratio outputtingprocess. Specifically, the microcomputer 30 outputs the command dutyratio set in S400 to the gate circuit 40. Then, the present process isterminated.

<1-2-6. Command Duty Ratio Setting Process>

A detailed description will be given of the command duty ratio settingprocess executed by the microcomputer 30 in S400, with reference to theflowchart in FIG. 7.

In S500, the microcomputer 30 executes a target duty ratio acquisitionprocess. Specifically, the microcomputer 30 acquires the target dutyratio inputted to the microcomputer 30 via the trigger switch 23.

In the present embodiment, the microcomputer 30 controls driving of themotor 60 so that the command duty ratio achieves the target duty ratio.The microcomputer 30 performs a soft start at a start-up of the motor 60in order to suppress an inrush-current into the motor 60. The soft startallows a gradual increase in the command duty ratio from zero to thetarget duty ratio after the trigger switch 23 is switched from OFF toON. An initial value of the command duty ratio is set to zero. Althoughthe initial value of the command duty ratio is set to zero in thepresent embodiment, the initial value may not necessarily be zero if theduty ratio is sufficiently low that can suppress the inrush-current.

In S510, the microcomputer 30 determines whether or not the command dutyratio at that point of time is smaller than the target duty ratioacquired in S500. When determining that the command duty ratio issmaller than the target duty ratio in S510, the microcomputer 30proceeds to process in S520.

In S520, the microcomputer 30 calculates an addition value in accordancewith the internal resistance value included in the internal resistanceinformation acquired from the battery pack 70, or, the addition value inaccordance with the internal resistance value calculated or estimatedfrom the internal resistance information. The addition value is a valueto be added to the command duty ratio at that point of time. A rate ofincrease in the command duty ratio is increased in accordance with anincrease in the addition value.

As shown in FIG. 8, when a term required for the command duty ratio toreach the target duty ratio is set constant in the soft start, voltageapplied to the motor 60 is increased in accordance with a decrease inthe internal resistance value. Accordingly, the value of the dischargecurrent flowing in the motor 60 is increased in accordance with thedecrease in the internal resistance value. Consequently, when theinternal resistance value is relatively small, the discharge currentvalue may exceed a threshold value of overcurrent and may result instopping of the motor 60 in the soft start. The threshold value ofovercurrent is, for example, 100 A. The discharge current value isdesirably suppressed to 70 to 80 A when the threshold value ofovercurrent is 100 A.

The microcomputer 30 changes the term required for the command dutyratio to reach the target duty ratio after the trigger switch 23 isswitched from OFF to ON based on the internal resistance value.Specifically, the microcomputer 30 calculates the addition value so thatthe addition value is decreased in accordance with the decrease in theinternal resistance value, thereby setting the rate of increase in thecommand duty ratio smaller in accordance with the decrease in theinternal resistance value. In the present embodiment, the command dutyratio at the start-up of the motor 60 corresponds to one example of thestarting parameter of the present disclosure.

In S530, the command duty ratio is updated to a value obtained by addingthe addition value to the command duty ratio at that point of time.

Meanwhile, in S510, when determining that the command duty ratio at thatpoint of time exceeds the target duty ratio, the microcomputer 30proceeds to process in S540.

In S540, the microcomputer 30 updates the command duty ratio to a valueobtained by subtracting a subtraction value from the command duty ratioat that point of time. The subtraction value is previously set and isconstant regardless of the internal resistance value. That is, in thepresent embodiment, when the command duty ratio is below the target dutyratio, the rate of increase in the command duty ratio is set smaller inaccordance with the decrease in the internal resistance value. On theother hand, when the command duty ratio exceeds the target duty ratio, arate of decrease in the command duty ratio is set constant regardless ofthe internal resistance value. Then, the present process is terminated.

<1-3. Operation>

Hereinafter, a description will be given of the command duty ratio andthe discharge current value at the start-up of the motor 60 when themicrocomputer 30 executes the command duty ratio setting process shownin FIG. 7, with reference to the time chart in FIG. 9.

When the trigger switch 23 is switched from OFF to ON, the command dutyratio and the discharge current value start to increase from zero. In acase where the internal resistance value is relatively small, the rateof increase in the command duty ratio is relatively small and thecommand duty ratio is increased relatively gradually, compared to a casewhere the internal resistance value is relatively large. Accordingly, ina case where the internal resistance value is relatively small, thedischarge current value is increased relatively gradually, compared to acase where the internal resistance value is relatively large.Consequently, a peak value of the discharge current value is suppressedbelow the threshold value of overcurrent, not only when the internalresistance value is relatively large but also when the internalresistance value is relatively small.

<1-4. Effects>

According to the above-described first embodiment, the following effectscan be obtained.

(1) The internal resistance information of the first, the second batterypacks 70A, 70B is acquired and control of the motor 60 is changed basedon the internal resistance information acquired. There is a possibilityof a delayed start-up of the electric working machine 10, when thebattery pack 70A having a relatively large internal resistance value iscoupled to the electric working machine 10 in which the control of themotor 60 is adapted to the battery pack 70B having a relatively smallinternal resistance value. On the other hand, the motor 60 may possiblystop because a current flows too much at a start-up of the electricworking machine 10 when the second battery pack 70B having a relativelysmall internal resistance value is coupled to the electric workingmachine 10 in which the control of the motor 60 is adapted to the firstbattery pack 70A having a relatively large internal resistance value.The control of the motor 60 is changed based on the internal resistanceinformation of the first, the second battery packs 70A, 70B, whereby anappropriately operable electric working machine 10 can be achieved.

(2) Control related to the start-up of the motor 60 is changed based onthe internal resistance information of the first, the second batterypacks 70A, 70B. This can suppress stopping due to overcurrent and thedelayed start-up of the motor 60 regardless of the internal resistancevalues of the first, the second battery packs 70A, 70B, and thus themotor 60 can be appropriately started.

(3) The command duty ratio at the start-up of the motor 60 is set basedon the internal resistance information of the first, the second batterypacks 70A, 70B, whereby the control related to the start-up of the motor60 can be changed in accordance with the internal resistance informationof the first, the second battery packs 70A, 70B.

(4) The term required for the command duty ratio to reach the targetduty ratio is changed based on the internal resistance information,whereby a flow of overcurrent into the motor 60 is suppressed regardlessof the internal resistance value.

(5) The rate of increase in the command duty ratio is changed inaccordance with the internal resistance value at the start-up of themotor 60, whereby the term required for the command duty ratio to reachthe target duty ratio can be changed.

(6) The command duty ratio is set so that the rate of change in thecommand duty ratio is decreased in accordance with the decrease in theinternal resistance value. This can suppress a sharp increase in currentvalue at the start-up of the motor 60 even when the internal resistancevalue is relatively small. Consequently, overcurrent at the star-up ofthe motor 60 can be suppressed even when the internal resistance valueis relatively small.

Second Embodiment

<2-1. Differences from First Embodiment>

The second embodiment has the same basic configuration as the firstembodiment. Thus, description on the common components is not repeated,and the difference will be mainly described. The same reference numeralsas those in the first embodiment indicate the same configuration, andthe reference of such configuration should be made to the precedingdescriptions.

In the first embodiment, the microcomputer 30 controls driving of themotor 60 so that the command duty ratio achieves the target duty ratio.On the other hand, in the second embodiment, the microcomputer 30executes a constant rotation speed control to control driving of themotor 60 so that the command rotation speed achieves the target rotationspeed. This is a difference from the first embodiment. The commandrotation speed is a command value of the rotation speed of the motor 60,and is set by the microcomputer 30. The target rotation speed is atarget value of the command rotation speed. In the first embodiment, thetarget duty ratio is inputted to the microcomputer 30 via the triggerswitch 23 and such. On the other hand, in the second embodiment, thetarget rotation speed is inputted to the microcomputer 30 via thetrigger switch 23 and such. This is another difference from the firstembodiment.

Specifically, the microcomputer 30 according to the second embodimentexecutes a process shown in the flowchart in FIG. 10 instead of aprocess shown in the flowchart in FIG. 6 in the motor driving process inS330. The constant rotation speed control is executed in the electricworking machine 10, such as a grass cutter, a hammer drill, and ablower, in which the rotation speed is desired not to be reduced when aload is increased. The constant rotation speed control according to thesecond embodiment and the duty control according to the first embodimentmay be switched in accordance with the operation mode.

<2-2. Processes>

<2-2-1. Motor Driving Process>

Hereinafter, a detailed description will be given of the motor drivingprocess executed by the microcomputer 30 in S330, with reference to theflowchart in FIG. 10.

In S600, the microcomputer 30 executes a command rotation speed settingprocess to set the command rotation speed. The command rotation speedsetting process will be detailed later.

In S610, the microcomputer 30 executes a command duty ratio calculationprocess. Specifically, the microcomputer 30 calculates the command dutyratio based on a difference between the rotation speeds so that anactual rotation speed is consistent with the command rotation speed. Thedifference between the rotation speeds is a difference between thecommand rotation speed set in S600 and the actual rotation speed of themotor 60 detected by the rotation speed detection sensor 26. That is tosay, the microcomputer 30 performs feedback control of the rotationspeed of the motor 60.

In S620, the microcomputer 30 executes a command duty ratio outputtingprocess in the same manner as the process in S410. Then, the presentprocess is terminated.

<2-2-2. Command Rotation Speed Setting Process>

Hereinafter, a detailed description will be given of the commandrotation speed setting process executed by the microcomputer 30 in S600,with reference to the flowchart in FIG. 11.

In S700, the microcomputer 30 executes a target rotation speedacquisition process. Specifically, the microcomputer 30 acquires thetarget rotation speed inputted to the microcomputer 30 via the triggerswitch 23 and such.

In the present embodiment, the microcomputer 30 controls driving of themotor 60 so that the command rotation speed is consistent with thetarget rotation speed. To start the motor 60, the microcomputer 30executes the soft start that allows a gradual increase in the commandrotation speed from zero to the target rotation speed. An initial valueof the command rotation speed is zero. Although the initial value of thecommand rotation speed is set to zero in the present embodiment, theinitial value may not necessarily be zero if the rotation speed issufficiently low to suppress an inrush-current.

In S710, the microcomputer 30 determines whether or not the commandrotation speed at that point of time is smaller than the target rotationspeed acquired in S700. When determining that the command rotation speedis smaller than the target rotation speed in S710, the microcomputer 30proceeds to process in S720.

In S720, the microcomputer 30 calculates an addition value in accordancewith the internal resistance value included in the internal resistanceinformation acquired from the battery pack 70, or the addition value inaccordance with the internal resistance value calculated or estimatedfrom the internal resistance information. The addition value is a valueto be added to the command rotation speed at that point of time. A rateof increase in the command rotation speed is increased in accordancewith an increase in the addition value.

As shown in FIG. 12, when a term required for the command rotation speedto reach the target rotation speed is set constant in the soft start, avoltage drop in the battery pack 70 is increased in accordance with anincrease in the internal resistance value. Accordingly, the value of thedischarge current flowing in the motor 60 is increased in accordancewith the increase in the internal resistance value. Consequently, whenthe internal resistance value is relatively large, the discharge currentvalue may exceed a threshold value of overcurrent in the soft start andmay result in stopping of the motor 60.

The microcomputer 30 then changes the term required for the commandrotation speed to reach the target rotation speed based on the internalresistance value after the trigger switch 23 is switched from OFF to ON.Specifically, the microcomputer 30 calculates the addition value so thatthe addition value is decreased in accordance with the increase in theinternal resistance value. In this way, the microcomputer 30 sets therate of change in the command rotation speed smaller in accordance withthe increase in the internal resistance value. In the presentembodiment, the command rotation speed at the start-up of the motor 60corresponds to one example of a startup parameter.

In S730, the command rotation speed is updated to a value obtained byadding the addition value to the command rotation speed at that point oftime.

Meanwhile, in S710, when determining that the command rotation speed atthat point of time exceeds the target rotation speed, the microcomputer30 proceeds to process in S740.

In S740, the microcomputer 30 updates the command rotation speed to avalue obtained by subtracting a subtraction value from the commandrotation speed at that point of time. The subtraction value ispreviously set and is constant regardless of the internal resistancevalue. That is, in the present embodiment, when the command rotationspeed is below the target rotation speed, the rate of increase in thecommand rotation speed is set smaller in accordance with the increase inthe internal resistance value. On the other hand, when the commandrotation speed exceeds the target rotation speed, a decreasing ratio ofthe command rotation speed is set constant regardless of the internalresistance value. Then, the present process is terminated.

<2-3. Operation>

Hereinafter, a description will be given of the command rotation speedand the discharge current value at the start-up of the motor 60 when themicrocomputer 30 executes the command rotation speed setting processshown in FIG. 11, with reference to the flowchart in FIG. 13.

In a case where the trigger switch 23 is switched from OFF to ON, thecommand rotation speed and the discharge current value start to beincreased from zero. In the internal resistance value is relativelylarge, the rate of increase in the command rotation speed is relativelysmall and the command rotation speed is increased relatively gradually,compared to a case where the internal resistance value is relativelysmall. Accordingly, in a case where the internal resistance value isrelatively large, the discharge current value is increased relativelygradually compared to a case where the internal resistance value isrelatively small. Consequently, the peak value of the discharge currentvalue is suppressed below the threshold value of overcurrent, not onlywhen the internal resistance value is relatively small but also when theinternal resistance value is relatively large.

<2-4. Effects>

According to the above-described second embodiment, the followingeffects in addition to effects (1) and (2) of the first embodiment canbe obtained.

(7) The command rotation speed at the start-up of the motor 60 is setbased on the internal resistance information of the first, the secondbattery packs 70A, 70B, whereby the control related to the start-up ofthe motor 60 can be changed in accordance with the internal resistanceinformation of the first, the second battery packs 70A, 70B.

(8) The term required for the command rotation speed to reach the targetrotation speed is changed based on the internal resistance information,whereby a flow of overcurrent into the motor 60 is suppressed regardlessof the internal resistance value.

(9) The rate of increase in the command rotation speed is changed inaccordance with the internal resistance value at the start-up of themotor 60, whereby the term required for the command rotation speed toreach the target rotation speed can be changed.

(10) The command rotation speed is set so that the rate of change in thecommand rotation speed is decreased in accordance with the increase inthe internal resistance value. This can suppress a sharp increase indischarge current value at the start-up of the motor 60 even when theinternal resistance value is relatively large. Consequently, overcurrentat the star-up of the motor 60 can be suppressed even when the internalresistance value is relatively large.

Third Embodiment

<3-1. Differences from Second Embodiment>

The third embodiment has the same basic configuration as the secondembodiment. Thus, description on the common components is not repeated,and the difference will be mainly described. The same reference numeralsas those in the second embodiment indicate the same configuration, andthe reference of such configuration should be made to the precedingdescriptions.

In the third embodiment, the microcomputer 30 performs the controlrelated to output restriction of the motor 60 in addition to theprocesses of the second embodiment. This is a difference from the secondembodiment. Specifically, the microcomputer 30 according to the thirdembodiment executes a process shown in the flowchart in FIG. 14 insteadof a process shown in the flowchart in FIG. 10 in the motor drivingprocess in S330.

<3-2. Process>

<3-2-1. Motor Driving Process>

Hereinafter, a detailed description will be given of the motor drivingprocess executed by the microcomputer 30 in S330, with reference to theflowchart in FIG. 14.

In S800, the microcomputer 30 executes the same process as in S600.

In S810, the microcomputer 30 executes a current limit value settingprocess. The current limit value setting process will be detailed later.

In S820, the microcomputer 30 executes a command duty ratio calculationprocess. Specifically, the microcomputer 30 calculates the command dutyratio so that: (I) the actual rotation speed is consistent with thecommand rotation speed; and (II) the value of discharge current flowingfrom the battery pack 70 to the electric working machine 10 is equal toor below the current limit value set in S810. If it is impossible thatboth of conditions described as (I) and (II) are satisfied, themicrocomputer 30 calculates the command duty ratio so that the actualrotation speed and the command rotation speed are as close as possiblewhile satisfying the condition (II), which has higher priority than thecondition (I).

In S830, the microcomputer 30 executes a command duty ratio outputtingprocess in the same manner as the process in S410. Then, the presentprocess is terminated.

<3-2-2. Current Limit Value Setting Process>

Hereinafter, a detailed description will be given of the current limitvalue setting process executed by the microcomputer 30 in S810, withreference to the flowchart in FIG. 15.

In S900, the microcomputer 30 sets the current limit value in accordancewith the internal resistance value of the battery pack 70. As shown inFIG. 16, when the value of discharge current flowing from the batterypack 70 to the electric working machine 10 is set constant, an outputvoltage value of the battery pack 70 is increased in accordance with thedecrease in the internal resistance value, and output of the motor 60 isincreased in accordance with the decrease in the internal resistancevalue.

The microcomputer 30 then sets the current limit value so that thecurrent limit value is decreased in accordance with the decrease in theinternal resistance value, whereby output of the motor 60 is notincreased when the internal resistance value is relatively smallcompared to a case where the internal resistance value is relativelylarge. For example, the current limit value is obtained by calculatingan expression “the internal resistance value×A+B”. Coefficients A and Bare positive integers. Then, the present process is terminated.

<3-3. Another Example of Third Embodiment>

Subsequently, another example of the third embodiment will be describedwith reference to FIGS. 17 to 20. In another example of the thirdembodiment, the microcomputer 30 performs authentication of the batterypack 70 via serial communication terminals 14A, 14B when the batterypack 70 is coupled to the electric working machine 10. Anyauthentication method may be used to authenticate the battery pack 70.For example, the microcomputer 30 transmits a generated authenticationcode to the battery pack 70, and receives a calculation resultcalculated by the battery pack 70 using the received authenticationcode. Then, the microcomputer 30 authenticates the battery pack 70 whena calculation result calculated by itself using the authentication codeis identical with the calculation result received from the battery pack70.

The microcomputer 30 sets control parameter of the motor 60 so as torestrict output of the motor 60 more in cases during authentication andwhere authentication is failed than a case where authentication issuccessful.

Specifically, as shown in FIG. 17, the microcomputer 30 sets in S810 thecurrent limit value smaller in a case during authentication of thebattery pack 70 than a case where authentication of the battery pack 70is successful. For example, the current limit value is set to 25 A whenauthentication is successful, and the current limit value is set to 20 Aduring authentication, regardless of the internal resistance value. Astate referred to as “during authentication” here corresponds to a statewhere authentication process by the microcomputer 30 is being executed,and a result on whether the authentication is successful or failed hasnot come out. During authentication, the motor 60 is rotatable byreceiving power supply from the battery pack 70.

As shown in FIG. 18, the microcomputer 30 sets the current limit valuefurther smaller in a case where authentication of the battery pack 70 isfailed than a case during authentication of the battery pack 70. Forexample, the microcomputer 30 sets the current limit value to 15A whenauthentication is failed regardless of the internal resistance value.

The microcomputer 30 may set the current limit value in accordance withthe internal resistance value in each of cases where authentication issuccessful, during authentication, and where authentication is failed.In these cases, for example, the coefficients A and B are set to smallervalues in the case during authentication than in the case whereauthentication is successful, and the coefficients A and B are set toeven smaller values in the case where authentication is failed than inthe case during authentication.

Further, the microcomputer 30 may change the internal resistance valuesof the battery pack 70 to be used for each of the cases whereauthentication is successful, during authentication and whereauthentication is failed. For example, as shown in FIG. 19, themicrocomputer 30 uses the internal resistance value acquired from thebattery pack 70 via serial communication when authentication issuccessful. The acquired internal resistance value is normally 200 mΩ ormore. On the other hand, the microcomputer 30, during authentication orwhen authentication is failed, uses the lowest internal resistancevalue, which is lower than an internal resistance value that can beacquired from the battery pack 70. The lowest internal resistance valueis, for example, 150 mΩ.

Further, the microcomputer 30 may set the current limit value inaccordance with a state of the battery pack 70. Specifically, themicrocomputer 30 calculates the overload counter value by accumulatingcount variations in accordance with the discharge current value at aspecified cycle using the overload map shown in FIG. 20. Themicrocomputer 30 sets the current limit value smaller when the overloadcounter value exceeds a previously-set counter threshold value than acase where the overload counter value is below the counter thresholdvalue.

At this time, the microcomputer 30 may use different overload maps foreach of cases where authentication is successful, during authenticationand where authentication is failed. For example, as shown in FIG. 19,the microcomputer 30 uses the overload map received from the batterypack 70 via serial communication when authentication is successful.

As shown in FIG. 20, the battery pack 70 is provided with the overloadmaps for battery types. The overload maps are provided for differentcount variations with respect to the same discharge current valueaccording to performance of the battery pack 70.

The microcomputer 30, when authentication is successful, acquires theoverload map from the battery pack 70 via serial communication.

The microcomputer 30, during authentication, uses the overload map forduring authentication previously set in the microcomputer 30. Also, themicrocomputer 30, when authentication is failed, uses the overload mapthat is previously set in the microcomputer 30 and is capable ofstopping the motor 60 the most quickly.

The microcomputer 30 may change the threshold value of overcurrent inaccordance with each of cases where authentication is successful, duringauthentication and where authentication is failed. For example, as shownin FIG. 19, the microcomputer 30, when authentication is successful,uses the threshold value of overcurrent acquired from the battery pack70 via serial communication. Normally, the acquired threshold value ofovercurrent is 200 A or more. On the other hand, the microcomputer 30,during authentication or when authentication is failed, uses the lowestthreshold value of overcurrent, which is lower than a threshold value ofovercurrent that can be acquired from the battery pack 70. The lowestthreshold value of overcurrent is, for example, 80 A.

<3-4. Effects>

According to the third embodiment, the following effects in addition toeffects (1) to (2), and (7) to (10) of the first embodiment can beobtained.

(11) The control related to output restriction of the motor 60 ischanged based on the internal resistance values of the first, the secondbattery packs 70A, 70B. In this way, output of the motor 60 can beappropriately controlled regardless of the internal resistance value.

(12) The current limit value is set so that the current limit value isdecreased in accordance with the decrease in the internal resistancevalue, whereby output of the motor can be controlled constant regardlessof the internal resistance values of the first, the second battery packs70A, 70B.

Other Embodiments

Although some embodiments of the present disclosure have been describedabove, it is to be understood that the present disclosure is not limitedto the above-described embodiments, but may be implemented in variousforms.

(a) Although the aforementioned embodiments exemplify the first, thesecond battery packs 70A, 70B including one battery block 80 or twobattery blocks 80 coupled in parallel, to be coupled to the electricworking machine 10, the battery pack is not limited to these. Thebattery pack coupled to the electric working machine 10 may be a batterypack including three or more battery blocks 80 coupled in parallel.

(b) The microcomputer 30 and the control circuit 75 may include acombination of a variety of individual electrical components instead ofa microcomputer or in addition to a microcomputer, or may include anApplication Specified Integrated Circuit (ASIC), an Application SpecificStandard Product (ASSP), a programmable logic device such as a FieldProgrammable Gate Array (FPGA), or a combination of these.

(c) Two or more functions performed by a single element in theaforementioned embodiments may be achieved by two or more elements, or afunction performed by a single element may be achieved by two or moreelements. Also, two or more functions performed by two or more elementsmay be achieved by a single element, or a function performed by two ormore elements may be achieved by a single element. Also, a part of aconfiguration in one of the aforementioned embodiments may be omitted.Further, at least a part of a configuration in one of the aforementionedembodiments may be added to, or may be replaced with, a configuration inanother one of the aforementioned embodiments.

(c) In addition to the electric working machine described above, thepresent disclosure can be realized in various forms such as a systemincluding the electric working machine as a component, a program forenabling the controller 20, a non-transitory tangible storage medium,e.g. a semiconductor memory storing the program, and a motor controlmethod.

What is claimed is:
 1. An electric working machine comprising: aconnection port configured to be coupled to a battery pack; a motorconfigured to be driven with electric power from the battery pack viathe connection port; a switch for driving the motor; and a controllerconfigured to acquire an internal resistance information related to aninternal resistance value of the battery pack via the connection port,the controller being configured to acquire the internal resistance valuebased on the internal resistance information, the controller beingconfigured to perform an open loop control of the motor based on a PulseWidth Modulation (PWM) signal of a command duty ratio, the command dutyratio being corresponding to a command value of a duty ratio of the PWMsignal, the controller being configured to perform a soft start inresponse to switching of the switch to ON in the open loop control inorder to gradually increase the command duty ratio to a target dutyratio, the target duty ratio being corresponding to a target value ofthe duty ratio, the controller being configured to set a first rate ofchange so that the first rate of change is decreased in accordance witha decrease in the internal resistance value in the soft start, and thefirst rate of change being corresponding to a rate of change in thecommand duty ratio.
 2. An electric working machine comprising: aconnection port configured to be coupled to a battery pack; a motorconfigured to be driven with electric power from the battery pack viathe connection port; a switch for driving the motor; and a controllerconfigured to acquire an internal resistance information related to aninternal resistance value of the battery pack via the connection port,the controller being configured to acquire the internal resistance valuebased on the internal resistance information, the controller beingconfigured to execute a constant rotation speed control to adjust arotation speed of the motor to be consistent with a command rotationspeed, the command rotation speed being corresponding to a command valueof the rotation speed, the controller being configured to perform a softstart in response to switching of the switch to ON in the constantrotation speed control in order to gradually increase the commandrotation speed to a target rotation speed, the target rotation speedbeing corresponding to a target value of the rotation speed, thecontroller being configured to set a second rate of change so that thesecond rate of change is decreased in accordance with the increase inthe internal resistance value in the soft start, and the second rate ofchange being corresponding to a rate of change in the command rotationspeed.
 3. An electric working machine comprising: a connection portconfigured to be coupled to a battery pack including one battery blockor more than one battery block; a motor configured to be driven withelectric power from the battery pack via the connection port; and acontroller configured to acquire an internal resistance informationrelated to an internal resistance value of the battery pack via theconnection port, the controller being configured to change control ofthe motor based on the internal resistance information acquired, theinternal resistance information indicating a number of battery blocksincluded in the battery pack or a model number of the battery pack. 4.The electric working machine according to claim 3, wherein the controlof the motor includes control related to a start-up of the motor.
 5. Theelectric working machine according to claim 4, wherein the controller isconfigured to set a startup parameter related to the start-up of themotor based on the internal resistance information.
 6. The electricworking machine according to claim 5, the electric working machinefurther comprising a switch for driving the motor, wherein thecontroller is configured to perform an open loop control of the motorbased on a Pulse Width Modulation (PWM) signal of a command duty ratio,the command duty ratio being corresponding to a command value of a dutyratio of the PWM signal, wherein the controller is configured to performa soft start in response to switching of the switch to ON in the openloop control in order to gradually increase the command duty ratio to atarget duty ratio, the target duty ratio being corresponding to a targetvalue of the duty ratio, and wherein the controller is configured tochange a first term based on the internal resistance information in thesoft start, the first term being corresponding to a time period requiredfor the command duty ratio to reach the target duty ratio in response toswitching of the switch to ON.
 7. The electric working machine accordingto claim 5, the electric working machine further comprising a switch fordriving the motor, wherein the controller is configured to execute aconstant rotation speed control to adjust a rotation speed of the motorto be consistent with a command rotation speed, the command rotationspeed being corresponding to a command value of the rotation speed,wherein the controller is configured to perform a soft start in responseto switching of the switch to ON in the constant rotation speed controlin order to gradually increase the command rotation speed to a targetrotation speed, the target rotation speed being corresponding to atarget value of the rotation speed, and wherein the controller isconfigured to change a second term based on the internal resistanceinformation in the soft start, the second term being corresponding to atime period required for the command rotation speed to reach the targetrotation speed in response to switching of the switch to ON.
 8. Theelectric working machine according to claim 6, wherein the startupparameter includes a first rate of change, the first rate of changebeing corresponding to a rate of change in the command duty ratio. 9.The electric working machine according to claim 8, wherein thecontroller is configured to acquire the internal resistance value basedon the internal resistance information, and wherein the controller isconfigured to set the first rate of change so that the first rate ofchange is decreased in accordance with a decrease in the internalresistance value.
 10. The electric working machine according to claim 7,wherein the startup parameter includes a second rate of change, thesecond rate of change being corresponding to a rate of change in thecommand rotation speed.
 11. The electric working machine according toclaim 10, wherein the controller is configured to acquire the internalresistance value based on the internal resistance information, andwherein the controller is configured to set the second rate of change sothat the second rate of change is decreased in accordance with anincrease in the internal resistance value.
 12. The electric workingmachine according to claim 3, wherein the control of the motor includescontrol related to output restriction of the motor.
 13. The electricworking machine according to claim 12, wherein the controller isconfigured to control a discharge current to be equal to or below a setcurrent limit value, the discharge current being flowing from thebattery pack to the motor, wherein the controller is configured toacquire the internal resistance value based on the internal resistanceinformation, and wherein the controller is configured to set the currentlimit value so that the current limit value is decreased in accordancewith a decrease in the internal resistance value.